[Freedreno] [PATCH 1/2] drm/msm: don't free the IRQ if it was not requested

[Abhinav Kumar]

On 5/6/2022 6:00 PM, Dmitry Baryshkov wrote:
> As msm_drm_uninit() is called from the msm_drm_init() error path,
> additional care should be necessary as not to call the free_irq() for
> the IRQ that was not requested before (because an error occured earlier
> than the request_irq() call).
> 
> This fixed the issue reported with the following backtrace:
> 
> [    8.571329] Trying to free already-free IRQ 187
> [    8.571339] WARNING: CPU: 0 PID: 76 at kernel/irq/manage.c:1895 free_irq+0x1e0/0x35c
> [    8.588746] Modules linked in: pmic_glink pdr_interface fastrpc qrtr_smd snd_soc_hdmi_codec msm fsa4480 gpu_sched drm_dp_aux_bus qrtr i2c_qcom_geni crct10dif_ce qcom_stats qcom_q6v5_pas drm_display_helper gpi qcom_pil_info drm_kms_helper qcom_q6v5 qcom_sysmon qcom_common qcom_glink_smem qcom_rng mdt_loader qmi_helpers phy_qcom_qmp ufs_qcom typec qnoc_sm8350 socinfo rmtfs_mem fuse drm ipv6
> [    8.624154] CPU: 0 PID: 76 Comm: kworker/u16:2 Not tainted 5.18.0-rc5-next-20220506-00033-g6cee8cab6089-dirty #419
> [    8.624161] Hardware name: Qualcomm Technologies, Inc. SM8350 HDK (DT)
> [    8.641496] Workqueue: events_unbound deferred_probe_work_func
> [    8.647510] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [    8.654681] pc : free_irq+0x1e0/0x35c
> [    8.658454] lr : free_irq+0x1e0/0x35c
> [    8.662228] sp : ffff800008ab3950
> [    8.665642] x29: ffff800008ab3950 x28: 0000000000000000 x27: ffff16350f56a700
> [    8.672994] x26: ffff1635025df080 x25: ffff16350251badc x24: ffff16350251bb90
> [    8.680343] x23: 0000000000000000 x22: 00000000000000bb x21: ffff16350e8f9800
> [    8.687690] x20: ffff16350251ba00 x19: ffff16350cbd5880 x18: ffffffffffffffff
> [    8.695039] x17: 0000000000000000 x16: ffffa2dd12179434 x15: ffffa2dd1431d02d
> [    8.702391] x14: 0000000000000000 x13: ffffa2dd1431d028 x12: 662d79646165726c
> [    8.709740] x11: ffffa2dd13fd2438 x10: 000000000000000a x9 : 00000000000000bb
> [    8.717111] x8 : ffffa2dd13fd23f0 x7 : ffff800008ab3750 x6 : 00000000fffff202
> [    8.724487] x5 : ffff16377e870a18 x4 : 00000000fffff202 x3 : ffff735a6ae1b000
> [    8.731851] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff1635015f8000
> [    8.739217] Call trace:
> [    8.741755]  free_irq+0x1e0/0x35c
> [    8.745198]  msm_drm_uninit.isra.0+0x14c/0x294 [msm]
> [    8.750548]  msm_drm_bind+0x28c/0x5d0 [msm]
> [    8.755081]  try_to_bring_up_aggregate_device+0x164/0x1d0
> [    8.760657]  __component_add+0xa0/0x170
> [    8.764626]  component_add+0x14/0x20
> [    8.768337]  dp_display_probe+0x2a4/0x464 [msm]
> [    8.773242]  platform_probe+0x68/0xe0
> [    8.777043]  really_probe.part.0+0x9c/0x28c
> [    8.781368]  __driver_probe_device+0x98/0x144
> [    8.785871]  driver_probe_device+0x40/0x140
> [    8.790191]  __device_attach_driver+0xb4/0x120
> [    8.794788]  bus_for_each_drv+0x78/0xd0
> [    8.798751]  __device_attach+0xdc/0x184
> [    8.802713]  device_initial_probe+0x14/0x20
> [    8.807031]  bus_probe_device+0x9c/0xa4
> [    8.810991]  deferred_probe_work_func+0x88/0xc0
> [    8.815667]  process_one_work+0x1d0/0x320
> [    8.819809]  worker_thread+0x14c/0x444
> [    8.823688]  kthread+0x10c/0x110
> [    8.827036]  ret_from_fork+0x10/0x20
> 
> Reported-by: Bjorn Andersson <bjorn.andersson at linaro.org>
> Fixes: f026e431cf86 ("drm/msm: Convert to Linux IRQ interfaces")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>

I was looking at how other drm drivers handle this and they also have a 
similar logic. So this is a good addition and thanks to the -EDEFER path 
getting exposed we finally uncovered this.

Reviewed-by: Abhinav Kumar <quic_abhinavk at quicinc.com>

> ---
>   drivers/gpu/drm/msm/msm_drv.c | 7 ++++++-
>   drivers/gpu/drm/msm/msm_kms.h | 1 +
>   2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 4a3dda23e3e0..44485363f37a 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -113,6 +113,8 @@ static int msm_irq_postinstall(struct drm_device *dev)
>   
>   static int msm_irq_install(struct drm_device *dev, unsigned int irq)
>   {
> +	struct msm_drm_private *priv = dev->dev_private;
> +	struct msm_kms *kms = priv->kms;
>   	int ret;
>   
>   	if (irq == IRQ_NOTCONNECTED)
> @@ -124,6 +126,8 @@ static int msm_irq_install(struct drm_device *dev, unsigned int irq)
>   	if (ret)
>   		return ret;
>   
> +	kms->irq_requested = true;
> +
>   	ret = msm_irq_postinstall(dev);
>   	if (ret) {
>   		free_irq(irq, dev);
> @@ -139,7 +143,8 @@ static void msm_irq_uninstall(struct drm_device *dev)
>   	struct msm_kms *kms = priv->kms;
>   
>   	kms->funcs->irq_uninstall(kms);
> -	free_irq(kms->irq, dev);
> +	if (kms->irq_requested)
> +		free_irq(kms->irq, dev);
>   }
>   
>   struct msm_vblank_work {
> diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h
> index ab25fff271f9..f8ed7588928c 100644
> --- a/drivers/gpu/drm/msm/msm_kms.h
> +++ b/drivers/gpu/drm/msm/msm_kms.h
> @@ -148,6 +148,7 @@ struct msm_kms {
>   
>   	/* irq number to be passed on to msm_irq_install */
>   	int irq;
> +	bool irq_requested;
>   
>   	/* mapper-id used to request GEM buffer mapped for scanout: */
>   	struct msm_gem_address_space *aspace;